
Lens tubes are ideal for creating compact optical subassemblies. The Ø1/2" lens tubes sold here can be used to house one or several optical elements. Optics are separated and secured by retaining rings that are positioned at the desired depth within the lens tube using our SPW603 spanner wrench. Depending on the item purchased, one or two retaining rings will be included (see below for details). Additional retaining rings can be purchased separately. In addition to the Ø1/2" lens tubes featured on this page, Thorlabs also offers Ø1", Ø30 mm, Ø2", and Ø3" versions, each of which is equipped with an SM series thread standard that depends on the tube diameter.

| Ø1/2" Shortcuts |
|---|
| Lens Tube Couplers SM Thread Adapters Lens Tube Mounts End Caps Kinematic Mounts Fixed Lens Mounts Rotational Mounts Translation Mounts |
| Lens Tube Compatible Products | |||||||
|---|---|---|---|---|---|---|---|
| Thread Adapters | Terminated Fiber Adapters | Collimation Package Adapters | LED and LD Mounts | Aspheric Lens Mounts | Irises, Apertures, and Shutters | Alignment Tools | |
Thorlabs' lens tubes utilize a series of non-standard threadings. Threading specifications are given below for our SM threadings utilized in our lens tube and cage system components so that you can machine mating components to suit your application. For threading specifications other than what is listed here, please contact Tech Support.
| SM05 Threading: Ø1/2" Lens Tubes, 16 mm Cage Systems | |||
|---|---|---|---|
| External Thread, 0.535"-40.0, UNS-2A | Internal Thread, 0.535"-40.0, UNS-2B | ||
| Max Major Diameter | 0.5340" | Min Major Diameter | 0.5350" |
| Min Major Diameter | 0.5289" | Min Pitch Diameter | 0.5188" |
| Max Pitch Diameter | 0.5178" | Max Pitch Diameter | 0.5230" |
| Min Pitch Diameter | 0.5146" | Min Minor Diameter (and 83.3% of thread) | 0.508" |
| Max Minor Diameter | 0.5069" | Max Minor Diameter (and 64.9% of thread) | 0.514" |
| SM1 Threading: Ø1" Lens Tubes, 30 mm Cage Systems | |||
|---|---|---|---|
| External Thread, 1.035"-40.0, UNS-2A | Internal Thread, 1.035"-40.0, UNS-2B | ||
| Max Major Diameter | 1.0339" | Min Major Diameter | 1.0350" |
| Min Major Diameter | 1.0288" | Min Pitch Diameter | 1.0188" |
| Max Pitch Diameter | 1.0177" | Max Pitch Diameter | 1.0234" |
| Min Pitch Diameter | 1.0142" | Min Minor Diameter (and 83.3% of thread) | 1.008" |
| Max Minor Diameter | 1.0068" | Max Minor Diameter (and 64.9% of thread) | 1.014" |
| SM30 Threading: Ø30 mm Lens Tubes | |||
|---|---|---|---|
| External Thread, M30.5x0.5 | Internal Thread, M30.5x0.5 | ||
| Max Major Diameter | 30.480 mm | Min Major Diameter | 30.500 mm |
| Min Major Diameter | 30.371 mm | Min Pitch Diameter | 30.175 mm |
| Max Pitch Diameter | 30.155 mm | Max Pitch Diameter | 30.302 mm |
| Min Pitch Diameter | 30.059 mm | Min Minor Diameter (and 83.3% of thread) | 29.959 mm |
| Max Minor Diameter | 29.938 mm | Max Minor Diameter (and 64.9% of thread) | 30.094 mm |
| SM2 Threading: Ø2" Lens Tubes, 60 mm Cage Systems | |||
|---|---|---|---|
| External Thread, 2.035"-40.0, UNS-2A | Internal Thread, 2.035"-40.0, UNS-2B | ||
| Max Major Diameter | 2.0338" | Min Major Diameter | 2.0350" |
| Min Major Diameter | 2.0287" | Min Pitch Diameter | 2.0188" |
| Max Pitch Diameter | 2.0176" | Max Pitch Diameter | 2.0239" |
| Min Pitch Diameter | 2.0137" | Min Minor Diameter (and 83.3% of thread) | 2.008" |
| Max Minor Diameter | 2.0067" | Max Minor Diameter (and 64.9% of thread) | 2.014" |
| SM3 Threading: Ø3" Lens Tubes | |||
|---|---|---|---|
| External Thread, 3.035"-40.0, UNS-2A | Internal Thread, 3.035"-40.0, UNS-2B | ||
| Max Major Diameter | 3.0337" | Min Major Diameter | 3.0350" |
| Min Major Diameter | 3.0286" | Min Pitch Diameter | 3.0188" |
| Max Pitch Diameter | 3.0175" | Max Pitch Diameter | 3.0242" |
| Min Pitch Diameter | 3.0133" | Min Minor Diameter (and 83.3% of thread) | 3.008" |
| Max Minor Diameter | 3.0066" | Max Minor Diameter (and 64.9% of thread) | 3.014" |
These stackable Ø1/2" lens tubes provide a fast and easy means for building compact optical assemblies. Their stackable design and direct interfacing with any SM05-threaded (0.535"-40) components provide flexibility for complex optomechanical assemblies. One SM05RR retaining ring is included with each lens tube.

| Item # | L1 | L2 | Thread Depth |
|---|---|---|---|
| SM05L03 | 0.41" | 0.08" | 0.3" |
| SM05L05 | 0.61" | 0.08" | 0.5" |
| SM05L10 | 1.11" | 0.08" | 1.0" |
| SM05L20 | 2.11" | 0.08" | 2.0" |
| SM05L30 | 3.11" | 0.08" | 3.0" |
| Alternatives | Ø1", Ø2", and Ø3" Stackable Lens Tubes | Ø1" and Ø2" Lens Tube Extensions | Ø1" and Ø2" Lens Tubes with Side Access Ports |
|---|
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
SM05L03 |
Lens Tube, Ø1/2", 0.30" Thread Depth |
$13.50 |
Today |
SM05L05 |
Lens Tube, Ø1/2", 0.50" Thread Depth |
$13.75 |
Today |
SM05L10 |
Lens Tube, Ø1/2", 1" Thread Depth |
$14.75 |
Today |
SM05L20 |
SM05 Lens Tube, 2" Thread Depth, One Retaining Ring Included |
$19.75 |
Today |
SM05L30 |
SM05 Lens Tube, 3" Thread Depth, One Retaining Ring Included |
$23.75 |
Today |

Unlike our Ø1/2" stackable lens tubes featured above, these internally threaded lens tubes do not feature a lip at one end nor do they have external SM05 threading. Therefore, optics housed inside can be accessed from both ends. To join these lens tubes end-to-end, use an SM05T2 Lens Tube Coupler. Two SM05RR retaining rings are included with each lens tube.
| Alternatives | Ø1" and Ø2" Lens Tubes Without External Threads | ||
|---|---|---|---|
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
SM05M05 |
Customer Inspired!SM05 Lens Tube Without External Threads, 1/2" Long, Two Retaining Rings Included |
$13.50 |
Today |
SM05M10 |
Customer Inspired!SM05 Lens Tube Without External Threads, 1" Long, Two Retaining Rings Included |
$14.75 |
Today |
SM05M20 |
Customer Inspired!SM05 Lens Tube Without External Threads, 2" Long, Two Retaining Rings Included |
$16.50 |
Today |
SM05M30 |
Customer Inspired!SM05 Lens Tube Without External Threads, 3" Long, Two Retaining Rings Included |
$18.00 |
Today |
Easy Access to Optics
Rotatable Slip Shield Protects Optics
Compatible with SM05-Threaded ComponentsThis stackable Ø1/2" lens tube with side slots provides a fast and easy means for building complex optical assemblies and adjusting the optics without disassembling the setup. Several optics can be inserted into a single tube using multiple SM05RR retaining rings. Simply thread the first retaining ring to the desired depth, add the optic, and then use a second retaining ring to secure the optic. Optics can be manually adjusted via the side slots without the use of a spanner wrench. The rotatable slip shield included with the lens tube fits over the lens tube slots to prevent unwanted light from entering the system and to keep the optical setup free from debris. Two retaining rings and one black plastic dust cover are included with each lens tube.
| Alternatives | Ø1" and Ø2" Slotted Lens Tubes | |
|---|---|---|
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
SM05L30C |
NEW! SM05 Slotted Lens Tube, 3" Thread Depth, 2 Retaining Rings Included |
$50.00 |
Today |
Thorlabs offers two different kinds of SM05 retaining rings. The SM05RR is our standard retaining ring that ships with our Ø1/2" lens tubes as well as many other Thorlabs components. If desirable, the SM05RR can be swapped out for a SM05LTRR, which is a retaining ring equipped with a Buna-N O-ring designed to reduce stress on the optical component and to produce a light-tight seal.
To position and adjust these retaining rings, choose one of our two spanner wrench options. The SPW603 Spanner Wrench has a hollow design that enables retaining rings for our SM05 series of lens tubes to be adjusted and installed without obscuring the beam path. The handle is knurled for improved grip. For use with longer lens tubes, multiple SPW603 spanning wrenches can be stacked to extend the wrench's maximum reach. Alternatively, the SPW801 Adjustable Spanner Wrench can also be used to position SM05RR or SM05LTRR retaining rings. Please note that the SPW801 wrench can withstand a maximum torque of 80 inch pounds. As an additional option, we also offer the SPB600 Spanner Wrench Bit Kit.
| Alternatives | Ø1", Ø2", and Ø3" Fixed Diameter Spanner Wrenches | Ø1", Ø2", and Ø3" Retaining Rings | |
|---|---|---|---|
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
SM05RR |
SM05 Retaining Ring for Ø1/2" Lens Tubes and Mounts |
$4.00 |
Today |
SM05LTRR |
SM05 Series Stress-Free Retaining Ring |
$18.40 |
Today |
SPW603 |
SM05 Spanner Wrench, Length = 1" |
$24.00 |
Today |
SPW801 |
Adjustable Spanner Wrench |
$95.90 |
Today |
SPW102 |
Adjustable Spanner Wrench, Replacement Blade Set |
$27.90 |
Today |
The SC05L24 lens tube cover is designed to fit over SM05 lens tubes and is used to provide both light and dust protection. For example, this cover can be used to span the gap between any two SM05 fixed lens tubes, thereby enclosing the light path in an optical setup. The SC05L24 is 24" long, but it can be cut to any desired length by the end user. Please note that we recommend using a fine-toothed sawblade to cut the cover.
| Alternatives | Ø1" and Ø2"Lens Tube Cover |
|---|
Part Number |
Description |
Price |
Availability |
|---|---|---|---|
SC05L24 |
Ø1/2" Slip-On Lens Tube Cover, 24" Long |
$11.00 |
Today |